Syntheses and Structure Investigations of 3d Transition Metal Complexes with a Flexible N<inf>4</inf>O<inf>2</inf>-Donor Hexadentate Schiff-Base Ligand

The syntheses and structure investigations of four new 3d transition metal complexes (1-4) with a flexible N4O2-donor hexadentate Schiff-base ligand are described; three complexes (1, 2, and 4) of FeIII, CoIII, and CuII metal ions have been investigated by UV-vis, FT-IR, high-resolution mass spectrometry (HR-MS), and scanning electron microscopy-electron dispersive spectroscopy, as well as single crystal X-ray diffraction. The X-ray structure of NiII complex 3 is also reported. The molecular structures of the complexes (1-3) demonstrate distorted octahedral coordination geometry, each exhibiting 1:1 (M:L) ratios and the CuII complex 4 shows a trinuclear structure with a CuII:L ratio of 3:2 in the solid state, which has been proven by X-ray diffraction. On the other hand, a mononuclear species of the CuII complex is formed in solution, which has been identified by electrospray ionization HR-MS